Generally, since a secondary battery may be charged and discharged unlike a primary battery, the secondary battery has been applied to various fields such as a digital camera, a cellular phone, a laptop computer, and a hybrid vehicle and has been actively studied. An example of the secondary battery includes a nickel-cadmium battery, a nickel-metal hydride battery, a nickel-hydrogen battery, and a lithium secondary battery. In addition, among these secondary batteries, the lithium secondary battery having a high energy density and a discharging voltage has been mainly studied, and has been commercialized and widely used.
Further, the secondary battery is configured in a form of a battery module in which a plurality of battery cells are stacked due to the necessity of a high output and a large capacity, and is configured of one battery pack by stacking and arranging a plurality of battery modules in parallel with each other and connecting positive electrode terminals and negative electrode terminals of neighboring battery modules to each other by bus bars.
Here, the bus bar is formed of a hard metal plate and has through-holes formed at both sides thereof, and the positive electrode terminal and the negative electrode terminal protruding outwardly of the battery modules are inserted into the through-holes and are fastened and are closely adhered and coupled thereto by a nut, such that the positive electrode terminal and the negative electrode terminal are electrically connected to each other.
However, since the bus bar as described above has the through-holes formed at both sides thereof and the electrode terminals are inserted into the through-holes, it is difficult to assemble the electrode terminals so as to be inserted into the through-holes of the bus bar due to a dimension tolerance, an assembling tolerance, or the like, between neighboring battery modules and electrode terminals.
In addition, the battery pack configured of the plurality of battery modules is installed in a vehicle, or the like, and is exposed to vibrations. In this case, since both sides of the bus bar are fixed to the electrode terminals, the electrode terminals of the battery modules and the bus bar are vulnerable to the vibrations, damage occurs or a fastening means becomes loose, such that a contact defect occurs.
As the related art, U.S. Pat. No. 7,458,862 entitled “Canted Coil Spring Power Terminal and Sequence Connection System” has been disclosed.